The present invention relates to a semiconductor device, and particularly to a technique capable of improving a mounting failure in a resin encapsulated semiconductor device and improving repairability thereof. This invention is particularly concerned with a technique effective for use in a resin encapsulated semiconductor device in which surface mounting is performed.
A resin encapsulated semiconductor device (hereinafter called xe2x80x9cIC packagexe2x80x9d) in which surface mounting is performed, comprises a semiconductor chip in which an integrated circuit including a semiconductor element is fabricated and built therein, a semiconductor chip mounting or loading portion such as a tub or heat sink on which the semiconductor chip is mounted, a plurality of inner leads electrically connected to their corresponding bonding pads of the semiconductor chip through bonding wires, outer leads integrally connected to the respective inner leads respectively, and a resin encapsulater which seals the semiconductor chip, semiconductor chip loading portion and respective inner leads with a resin. The exposing of a main surface of the semiconductor chip loading portion, which is located on the side opposite to a main surface thereof on the semiconductor chip loading side, from a surface below the resin encapsulater is considered as means for enhancing heat radiation performance in the present resin encapsulated semiconductor device.
Examples descriptive of a resin encapsulated semiconductor device wherein surface mounting is carried out in which a tub corresponding to a semiconductor chip loading portion is exposed or made bare to a surface below a resin encapsulater, have been disclosed in Japanese Patent Application Laid-Open Nos. Hei 4-317360 and 5-291459 and Sho 61-216454. Further, an example of a resin encapsulated semiconductor device wherein surface mounting is performed in which a heat sink corresponding to a semiconductor chip loading portion is exposed from a surface below a resin encapsulater, has been disclosed in Japanese Patent Application Laid-Open No. Hei 8-130273. In the package wherein the tub or heat sink is made bare to the surface below each of these resin encapsulaters, the exposed tub or heat sink is soldered to each land of a printed wiring board serving as a printed circuit board, whereby the generated heat of a chip can be radiated from the tub or heat sink to the printed wiring board through soldered portions by thermal conduction.
In the above-described resin encapsulated semiconductor device, however, the semiconductor chip loading portion such as the tub or heat sink with the semiconductor chip mounted thereon increases in size as the semiconductor chip increases in size. It has been defined by the inventors that when such a resin encapsulated semiconductor device is soldered to lands on a printed circuit board, molten solder below the semiconductor chip loading portion is made one-sided or unbalanced as shown in FIG. 20, so that a mounting failure occurs that the resin encapsulated semiconductor device is inclined and leads on the floated side of the resin encapsulated semiconductor device are not connected to their corresponding lands on the printed circuit board. A problem that when a resin encapsulated semiconductor device surface-mounted on a printed circuit board is taken off from the printed circuit board for the purpose of repair (e.g., repair at a mounting test, repair in its practical use and the like) resultant from some reasons even where the above-described mounting failure is not produced, heat to melt solder is hard to be transferred to a central portion of a solder connecting surface of a semiconductor chip loading portion such as the tub or heat sink connected to lands on the printed circuit board by solder, and repairability is also poor, has been also revealed by the inventors.
An object of the present invention is to provide a resin encapsulated semiconductor device capable of preventing the inclination thereof upon surface mounting thereof onto a printed circuit board to thereby prevent a mounting failure from occurring.
Another object of the present invention is to provide a resin encapsulated semiconductor device capable of improving repairability of the resin encapsulated semiconductor device surface-mounted on a printed circuit board.
A further object of the present invention is to provide a method of manufacturing a resin encapsulated semiconductor device, which is capable of preventing the inclination thereof upon surface mounting thereof on a printed circuit board and thereby preventing a mounting failure from occurring.
A still further object of the present invention is to provide a method of manufacturing a resin encapsulated semiconductor device, which is capable of improving repairability of the resin encapsulated semiconductor device surface-mounted on a printed circuit board.
A still further object of the present invention is to provide a mount structure wherein a resin encapsulated semiconductor device surface-mounted on a printed circuit board is mounted on the printed circuit board without its inclination on the printed circuit board.
The above, other objects and novel features of the present invention will become apparent from the description of the specification of the present application and the accompanying drawings.
Summaries of typical ones of the inventions disclosed in the present application will be explained in brief as follows.
Namely, a resin encapsulated semiconductor device according to one aspect of the present invention comprises a resin encapsulater, a semiconductor chip located within the resin encapsulater and having a plurality of electrodes on one main surface, a semiconductor chip loading portion disposed within the resin encapsulater and having a loaded surface for mounting the semiconductor chip thereon and an unloaded surface provided on the side opposite to the loaded surface, and a plurality of input/output leads which are connected to the plurality of electrodes to input signals to the plurality of electrodes of the semiconductor chip or output signals from the plurality of electrodes thereof and which extend outside the resin encapsulater, and wherein the unloaded surface of the semiconductor chip loading portion comprises a plurality of regions separated from one another and the plurality of regions are exposed from the resin encapsulater.
A resin encapsulated semiconductor device according to another aspect of the present invention comprises a semiconductor chip having a plurality of electrodes on one main surface, a semiconductor chip loading portion having a main surface on which the semiconductor chip is mounted, a plurality of input/output leads which are connected to the plurality of electrodes to input signals to the plurality of electrodes of the semiconductor chip or output signals from the plurality of electrodes thereof and which extend in a direction far away from the semiconductor chip, and a resin encapsulater which seals the semiconductor chip, the semiconductor chip loading portion and some of the plurality of input/output leads, and wherein the other main surface of the semiconductor chip loading portion, which is provided on the side opposite to the main surface on which the semiconductor chip is mounted, is separated into a plurality of regions by a substance hard to be wet with a brazing filler metal and exposed from the resin encapsulater.
A resin encapsulated semiconductor device according to a further aspect of the present invention comprises a semiconductor chip having a plurality of electrodes on one main surface, a semiconductor chip loading portion having a main surface on which the semiconductor chip is mounted, a plurality of inner leads having one ends adjacent to the semiconductor chip, a plurality of outer leads integral with the plurality of inner leads respectively, connectors which respectively electrically connect the plurality of electrodes of the semiconductor chip and the plurality of inner leads to one another, and a resin encapsulater which seals the semiconductor chip, the semiconductor chip loading portion and the plurality of inner leads, and wherein the other main surface of the semiconductor chip loading portion, which is provided on the side opposite to the main surface on which the semiconductor chip is mounted, is exposed from the resin encapsulater, and the other main surface of the semiconductor chip loading portion, which is exposed from the resin encapsulater, is comprised of a plurality of exposed regions separated from one another by a substance hard to be wet with a brazing filler metal.
A resin encapsulated semiconductor device according to a still further aspect of the present invention comprises a semiconductor chip having a plurality of electrodes on one main surface, a semiconductor chip loading portion having a main surface on which the semiconductor chip is mounted, a plurality of inner leads having one ends adjacent to the semiconductor chip, a plurality of outer leads integral with the plurality of inner leads respectively, connectors which respectively electrically connect the plurality of electrodes of the semiconductor chip and the plurality of inner leads to one another, and a resin encapsulater which seals the semiconductor chip, the semiconductor chip loading portion and the plurality of inner leads, and wherein the other main surface of the semiconductor chip loading portion, which is provided on the side opposite to the main surface on which the semiconductor chip is mounted, is exposed from the resin encapsulater, and the other main surface of the semiconductor chip loading portion, which is exposed from the resin encapsulater, is comprised of a plurality of exposed regions separated from one another by a resin embedded in the semiconductor chip loading portion from the other main surface of the semiconductor chip loading portion.
A resin encapsulated semiconductor device according to a still further aspect of the present invention comprises a resin encapsulater, a semiconductor chip located inside the resin encapsulater and having a plurality of electrodes on one main surface, a semiconductor chip loading portion having a loaded surface for mounting the semiconductor chip thereon and an unloaded surface provided on the side opposite to the loaded surface, a plurality of inner leads having one ends adjacent to the semiconductor chip, and connectors which respectively electrically connect the plurality of electrodes of the semiconductor chip and the plurality of inner leads to one another, and wherein the other ends of the plurality of inner leads are integral with a plurality of outer leads extending outside the resin encapsulater, and the unloaded surface of the semiconductor chip loading portion is comprised of a plurality of regions separated from one another by a solder resist, which are exposed from one surface of the resin encapsulater.
A resin encapsulated semiconductor device according to a still further aspect of the present invention comprises a resin encapsulater, a semiconductor chip having a plurality of electrodes on one main surface, a semiconductor chip loading portion having a loaded surface for mounting the semiconductor chip thereon and an unloaded surface provided on the side opposite to the loaded surface, a plurality of inner leads having one ends adjacent to the semiconductor chip, and connectors which respectively electrically connect the plurality of electrodes of the semiconductor chip and the plurality of inner leads to one another, and wherein the other ends of the plurality of inner leads are integral with a plurality of outer leads extending outside the resin encapsulater, and the unloaded surface of the semiconductor chip loading portion is comprised of a plurality of regions separated from one another by a substance hard to be wet with solder which selectively protrude from the unloaded surface, which regions are exposed from one surface of the resin encapsulater.
A resin encapsulated semiconductor device according to a still further aspect of the present invention comprises a semiconductor chip having a plurality of electrodes on one main surface, a tub having a main surface on which the semiconductor chip is mounted, a plurality of inner leads having one ends adjacent to the semiconductor chip, a plurality of outer leads integral with the plurality of inner leads respectively, connectors which respectively electrically connect the plurality of electrodes of the semiconductor chip and the inner leads to one another, and a resin encapsulater which seals the semiconductor chip, the tub and the plurality of inner leads, and wherein the other main surface of the tub, which is provided on the side opposite to the main surface on which the semiconductor chip is mounted, is exposed from the resin encapsulater, and the other main surface of the tub, which is exposed from the resin encapsulater, is comprised of a plurality of exposed regions separated from one another by a substance hard to be wet with solder.
A resin encapsulated semiconductor device according to a still further aspect of the present invention comprises a semiconductor chip having a plurality of electrodes on one main surface, a heat sink having a main surface on which the semiconductor chip is mounted, a plurality of inner leads having one ends adjacent to the periphery of the semiconductor chip, a plurality of outer leads integral with the plurality of inner leads respectively, connectors which respectively electrically connect the plurality of electrodes of the semiconductor chip and the inner leads to one another, and a resin encapsulater which seals the semiconductor chip, the heat sink and the plurality of inner leads, and wherein the other main surface of the heat sink, which is provided on the side opposite to the main surface on which the semiconductor chip is mounted, is exposed from the resin encapsulater, and the other main surface of the heat sink, which is exposed from the resin encapsulater, is comprised of a plurality of exposed regions separated from one another by a substance hard to be wet with solder.
Further, a method of manufacturing a resin encapsulated semiconductor device, according to one aspect of the present invention, comprises the following steps: a step for preparing a lead frame having a semiconductor chip loading portion including a main surface with a semiconductor chip mounted thereon and the other main surface provided on the side opposite to the main surface and positioned below the main surface, and recessed portions which are defined in the other main surface and separate the other main surface into plural form; and a plurality of leads each having a first surface placed adjacent to the semiconductor chip loading portion and a second surface provided on the side opposite to the first surface, located below the first surface and located above the other main surface of the semiconductor chip loading portion; a step for preparing a semiconductor chip having a plurality of electrodes on one main surface; a step for connecting the semiconductor chip to the main surface of the semiconductor chip loading portion of the lead frame; a step for connecting the plurality of leads and the plurality of electrodes provided on one main surface of the semiconductor chip to one another by connecting means; and a step for placing the lead frame connected with the semiconductor chip so that the other main surface of the semiconductor chip loading portion makes contact with a cavity surface of a mold having a cavity and sealing the semiconductor chip, some of the plurality of leads and the semiconductor chip loading portion by a resin.
Furthermore, a mount structure according to one aspect of the present invention comprises a semiconductor device including a semiconductor chip having a plurality of electrodes on one main surface, a semiconductor chip loading portion having a main surface on which the semiconductor chip is mounted, a plurality of input/output leads which are respectively connected to the plurality of electrodes to input signals to the plurality of electrodes of the semiconductor chip or output signals from the plurality of electrodes thereof and extend in a direction far away from the semiconductor chip, and a resin encapsulater which seals the semiconductor chip, the semiconductor chip loading portion and some of the plurality of input/output leads and wherein the other main surface of the semiconductor chip loading portion, which is located on the side opposite to the main surface on which the semiconductor chip is mounted, is separated into a plurality of regions by a substance hard to be wet with a brazing filler metal, and exposed from the resin encapsulater; and a printed circuit board having a surface on which a plurality of first lands having the same patterns as the plurality of exposed regions constituting an unloaded surface of the semiconductor chip loading portion of the semiconductor device and a plurality of second lands corresponding to the plurality of input/output leads of the semiconductor device are formed; and wherein the semiconductor device is soldered to the plurality of first and second lands.
A mount structure according to another aspect of the present invention comprises a semiconductor device including a semiconductor chip having a plurality of electrodes on one main surface, a semiconductor chip loading portion having a main surface on which the semiconductor chip is mounted, a plurality of inner leads having one ends adjacent to the semiconductor chip, a plurality of outer leads integral with the plurality of inner leads respectively, connectors which respectively electrically connect the plurality of electrodes of the semiconductor chip and the plurality of inner leads to one another, and a resin encapsulater which seals the semiconductor chip, the semiconductor chip loading portion and the plurality of inner leads and wherein the other main surface of the semiconductor chip loading portion, which is located on the side opposite to the main surface on which the semiconductor chip is mounted, is exposed from the resin encapsulater, and the other main surface of the semiconductor chip loading portion, which is exposed from the resin encapsulater, is comprised of a plurality of exposed regions separated from one another by a resin embedded in the semiconductor chip loading portion from the other main surface of the semiconductor chip loading portion; and a printed circuit board having a surface on which a plurality of first lands having the same patterns as the plurality of exposed regions constituting the other main surface of the semiconductor chip loading portion of the semiconductor device and a plurality of second lands corresponding to the plurality of outer leads of the semiconductor device are formed; and wherein the semiconductor device is soldered to the plurality of first and second lands of the printed circuit board.